Cathy Featherstone has kindly produced this explanation of why she 
believes the evidence is that creamatocrits have no appropriate use 
in the general clinical assessment of lactating women. She cannot 
post to Lactnet direct because of an email problem, but is happy for 
me to send her post instead.

These are her words:

>
>
>I dont believe there is currently any application for the use of
>creamatocrits as a diagnostic tool in the general clinical assessment
>of lactating women. The only exception being the engineering of higher
>fat feeds for VLBW babies or lower fat feeds in chylothorax.
>
>A single creamocrit is a snapshot in time that will measure the
>percentage of fat in that particular sample and is not representative
>of anything that can be applied to either milk production, milk
>transfer or weight gain. There is no baseline "normal value" for a
>single creamatocrit sample. There are 2 points I'd like to make.
>
>1. Several studies have shown the essential factor related to infant
>growth is the volume of milk consumed and NOT the concentration of fat
>(or anything else) in milk (VLBW infants being the exception). The
>average fat content can vary considerably between women who have
>thriving babies. an eg is one mother who averaged around 30g/L and
>another around 62g/L (see Cregan & Hartmann, Computerised Breast
>Measurement from Conception to Weaning: Clinical Implications 1999
>15(2) JHL, for a very nice discussion of all of these concepts)


(My comments - look at this difference! Two mothers, each with 
thriving babies, and one produces a sample with *half* the fat 
content of the other...in their particular samples)

>
>2. There was a comment in regard to creamatocrits about Hartmann
>research showing there was higher "calorie milk" with low production
>than with higher milk productions. This can be open to
>misinterpetation. What the Hartmann team's research showed was that
>the emptier the breast (low degree of fullness) the higher the fat
>content of that milk sample and that the women with lower storage
>capacities (but this doesn't mean a lower milk production) had a more
>consistent concentration (less variation) of fat in milk when
>measuring the differences between fore and hindmilk samples, than
>women with higher storage capacities. That is: the higher the degree
>of fullness the greater the variation between fore and hind milk
>creamatocrits, the lower the degree of breast fullness the less
>variation. Degree of fullness (and hence fat content) of the breast is
>highly variable throughout the day and is influenced by many things
>but in particular is the time since the last feed, and storage
>capacity.


(My comments - another clear reason why taking a sample of a mother's 
milk is pointless and irrelevant)

>
>The only meaningful use for creamatocrits in the context of weight
>gain is in the measurement of total milk production. This involves
>taking a milk sample before (foremilk) and after (hindmilk) every feed
>from each breast for every feed for 24 hours plus one breastfeed. In
>addition the baby has to be test weighed before and after each feed
>from each breast when the samples are taken. Using creamtocrits from
>before and after every feed from each breast plus measurement of milk
>transfer from the test weighs,  a formula  can then be used to measure
>Total milk production for that 24 hours. This is OK for research but
>not something that would generally have a practical application for
>clinical situations.


(My comment - such interventionist treatment is likely to be 
difficult to do accurately, and will certainly disturb the responsive 
nursing relationship between mother and baby)

>
>A single creamatocrit  is meaningless and lends nothing to the
>clinical picture. A creamatocrit taken before and following a feed may
>give us an indication of the emptying of the breast at that feed (but
>frankly nothing wrong with observing baby swallowing at breast and
>feeling the breast to estimate degree of emptying,  or if we really
>need to, a test weigh  but then again we have to remember, this only
>ONE feed).


(My comment - it's surely rare that we need to 'estimate the degree 
of emptying' in this way. We can certainly guage an effective feed, 
in terms of 'did this baby get what he wanted and needed?'  without 
doing this estimation, with or without the (useless? irrelevant? 
risky?) crematocrit...and as Cathy says, it is only ONE feed, anyway. 
)

>
>I have seen a research study on expressing that recommends
>creamatocrit surveillance provides a positive tool to ensure effective
>milk expression. But again surveillance is the key word, one off
>samples are no use to anyone and one has to ask even if "surveillance"
>tells us milk expression is not effective, we probably knew this
>anyway from simply observing expression volumes and patterns over
>time.
>
>Best wishes
>Cathy Fetherston RM PhD IBCLC
>Perth, Western Australia


Heather Welford Neil
NCT bfc, tutor, UK

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